Structural members are available in a wide variety of configurations to provide structural support under a variety of loading conditions. In particular, the fuselage, wings, and empennage of an aircraft typically include structural members called stringers or longerons that are coupled to skin members on the fuselage, wing, and empennage surfaces that cooperatively provide flexural and torsional stiffness to these portions of an aircraft. Traditionally, the fuselage, wing, stabilizers, and empennage surfaces are fabricated from a metal, such as without limitation, aluminum, steel or titanium. The stringer may include a planar wall portion that is generally oriented in a direction approximately perpendicular to the skin member and extending in a generally length wise direction along the fuselage and empennage surface and generally spanwise direction along the wing or stabilizer so that the web portion offers resistance to bending. A flange portion may be positioned on one or both of the longitudinal edges of the web portion in order to provide increased rigidity and support to the stringer. The flange portion further allows the stringer to be coupled to the skin member by providing an attachment surface.
Fiber-reinforced composite materials are also available that may be used to form various structural members, and may be used as a substitute for metals, particularly in applications where relatively low weight and high mechanical strength is desired. As a result, fiber-reinforced composite materials are widely used in a variety of commercial and military aircraft, terrestrial vehicles and consumer products. The material is generally comprised of a network of reinforcing fibers that are generally applied in layers (e.g., plies), and a polymeric resin that substantially wets the reinforcing fibers to form an intimate contact between the resin and the reinforcing fibers. The material may be formed into a structural component by a variety of known forming methods, such as an extrusion process or other forming processes. The use of fiber-reinforced composite materials may have drawbacks including increased complexity in the manufacture and assembly of such materials, additional expense, and creation of waste when materials are improperly cured.
Although desirable results have been achieved using prior art apparatus and methods, a stringer and skin structure that may be fabricated at a low cost and result in a more integrated structure would have utility.